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Jan. 27, 2011 -- The CDC has issued early recommendations for the use of AIDS drugs to prevent HIV infection of men who have high-risk sex with men.

The preliminary guidelines follow last November's groundbreaking report that daily use of the AIDS drug Truvada lowers men's risk of HIV infection. This strategy, called pre-exposure prophylaxis or PrEP, can cut HIV risk by as much as 92% in men who take the pill every day.

But there's a catch. Several catches. For example:

Truvada has to be taken every day, not just prior to sex.

Truvada, like all HIV drugs, has side effects.

Drug-resistant virus develops in men who begin PrEP when already infected with HIV.

PrEP does not prevent other dangerous sexually transmitted diseases.

Truvada is expensive. Since PrEP is not an FDA-approved use of the drug, insurance may not cover the cost.

U.S. public health agencies are developing PrEP guidelines. But since the news is out -- and men already are asking their doctors whether PrEP is right for them -- the CDC today issued preliminary guidelines.

Since PrEP was tested only in men (and male-to-female transgendered women), PrEP should be given only to biological males. Men eligible for PrEP should be at high risk of HIV infection -- that is, they should frequently change sexual partners or have concurrent partners in a region with high HIV prevalence.

Preliminary PrEP Guidelines

Here's the CDC's basic advice:

PrEP should be offered only to HIV-negative men at high risk of HIV infection.